Firstly, good luck to everyone who's applied to grad school and congratz to those who got accepted!

I'm currently a junior that transferred to a university with a pretty good Physics Rep in California. So I currently have a 4.0 and doing research in Plasma. I want to go to grad school, but there's a small problem.
My physics department has a set core of classes that we take to graduate. Then there are "Recommended" classes that I should take if I want to go to grad school, that are not required for graduation. Classes such as 'complex analysis', 'general relativity' (Yikes!), 'nuclear physics',.....etc.
Being a transfer, I started upper divs a bit late (relative to others), and can probably complete the major requirements + maybe 5/10 of the recommended courses in the next 2 years. I MIGHT be able to cram a bit more of the classes into my schedule, but this seriously puts my gpa at risk. (I'm talking 5 upper div classes per quarter on top of research).
So is it better to demonstrate a (B to A-) level of understanding while taking a lot per quarter, or should I just stick with 3-4 upper div classes, maintain my high gpa, and graduate as a "basic" student?
I'd like to hear your insight. Thanks!